1. Field of the Invention
The present invention relates to an antenna structure, in particular, to a multi-input multi-output antenna system capable of covering several wireless local area network frequency bands.
2. Description of Related Art
For various wireless communications devices and products, an antenna is a necessary and indispensable component, which functions as a major component for determining whether or not a communications product can receive radio waves successfully. As wireless communications products and consumer electronic products become more diversified, the design requirements for an antenna also become increasingly higher, so that the design requirement for the antenna must consider the receiving/transmitting performance along with the aesthetic style of the design results, and furthermore, the antenna design must also satisfy the electromagnetic wave characteristics of different wireless communications technologies. The end results are that the antenna technology keeps broadening the bandwidth and minimizing the size of the antenna.
As the wireless communications technology blooms, the demand for antennas increases drastically, and related applications in the areas of mobile phones, notebook computers, global positioning systems, and digital televisions currently rely on antennas for transmitting and receiving signals. The antenna is a necessary device for wireless communications devices and products to communicate with the outside world, since it is responsible for transmitting and receiving wireless signals. As an important component of a radio frequency system, the antenna has a substantial effect on the signal receiving quality and the overall performance of the wireless communications system. Therefore, since the user requirements are becoming higher in regard to stylish design, power saving function, transmission rate, and transmission range, and due to the fact that applications in different geographical areas have different requirements for the antennas, the design of antennas is becoming a more server technical challenge.
Most wireless local area network or 802.11a/b/g/n access-point antennas come with an external antenna structure. The most common antenna is a dipole antenna wrapped with plastic/rubber sleeves, and an antenna system of this sort is generally composed of a single frequency of 2.4 GHz or a dual frequency of 2.4/5 GHz; wherein the height of such antenna system is generally triple the thickness of the wireless broadband router/hub device, and the antenna is protruding and rises from the top of a casing of the device. However, the additional plastic/rubber sleeves connected to the periphery of the antenna incur a higher manufacturing cost and a higher level of difficulty for manufacturing the aforementioned antennas in terms of achieving mass production and assuring practical applications. Furthermore, the antenna is fixed by an external mechanical part for its operation, and the antenna of this sort cannot be built-in or hidden inside a general wireless broadband router/hub device, and thus the antenna is exposed to the outside from the casing, thereby substantially reducing the aesthetic appearance of the product. In addition, users need to install the antenna, and adjust the signal receiving position of the antenna before its use, and thus the operation is relatively inconvenient. The antenna also has the disadvantages of being damaged by external forces easily, occupying much space, and ruining an overall aesthetic appearance.
In view of the aforementioned shortcomings of the prior art, the inventor of the present invention discloses a reasonable and effective design to overcome the shortcomings of the prior art.